I'm not an expert by any means....but this sounds like a decent deal to me. From what I know, Sony Vaios are solid. I own a laptop with single core 2.0 processor and 2gb RAM and Vista Home Premium (no SP1) runs quite well with those specs. You might want to think of adding a cooling fan for this. One of the reviews I read talked about the computer getting warm. It's certainly normal for heat to happen but a fan will keep it from overheating.
And grab one of the Logitech V220 wireless mouses from circuitcity.com for 9.99 AR. I consider mine priceless. It has worked flawlessly for me. See link on gottadeal.com homepage for this deal. HTH.